Strange Error on Home Page

One of the subdomain sites is working fine: but the main site has this message:
Warning: require_once(/home/metatro4/public_html/ failed to open stream: No such file or directory in /home/metatro4/public_html/ on line 81

Fatal error: require_once(): Failed opening required '' (include_path='.:disappointed:usr/local/php56/pear') in /home/metatro4/public_html/ on line 81

Thanks for looking into it:slight_smile: